Hydrocarbons n -hexane

Aliphatic hydrocarbons n-hexane, cyclohexane, and n-heptane Aliphatic hydrocarbons are nonpolar. Their solubility in water is virtually nil. They are less dense than water, and thus would be the top layer in a separatory funnel with a water solution. They are obviously poor solvents for polar compounds, but are very good for extracting traces of nonpolar solutes from water solutions. They are highly flammable and have a low toxicity level. 

The compounds studied were divided into two groups, based on their adsorption activity, as highly reactive and relatively unreactive compounds. Organic compounds adsorb through electron donation to the metal surface (Fischer et al., 1977 Stair, 1982). The two saturated hydrocarbons, n-hexane and... 

Adsorption Using data from Table 5.1 Adsorption of organic compounds on the metal surface under static conditions and on the nascent steel surfaces , discuss the adsorption activity for each of the following (a) saturated hydrocarbons (n-hexane, cyclohexane), (b) the compounds which have rr-electrons (benzene, 1-hexene), (c) compounds with functional polar groups (propylamine, propionic acid). 

As described above, immersion calorimetry constitutes a powerful technique for the textural and chemical characterization of porous solids. In the absence of specific adsorbate-adsorbent interactions, heats of immersion can be related to the surface area available for the molecules of the liquid. However, the use of polar molecules or molecules with functional groups produces specific adsorbent-adsorbate interactions related to the surface chemical properties of the solid. An adequate selection of the immersion liquid can be used to study hydrophilicity, acid-base character, etc. Table 2 reports the enthalpies of immersion (J/g) into different lineal and branched hydrocarbons (n-hexane, 2-methyl-pentane and 2,2-dimethyl-butane) for Zn exchanged NaX zeolites. 

The set of test molecules used here for port gauging of zeolites all enter freely at room temperature into the AlP04-5, SAPO-5, and SSZ-24 sieves. These molecules include six C-6 hydrocarbons - n-hexane (nC6), benzene, 3-methylpentane (3MP), methyl cyclopentane, cyclohexane and 2, 2-dimethylbutane (22DMB) - and iso-octane. The total adsorption of this mixture of hydrocarbons is about 0.12 ml/g for these sieves. The admission of the larger molecules such as 22DMB is compatible with the 12-ring pore openings of the sieves. 

Proof of the high reactivity of the unsaturated units present in the elastomers we used was obtained by polymerizing vinyl chloride in the presence of different amounts of two hydrocarbons, n-hexane and 2-methyl-2-butene these may be taken as models of the saturated polyhydrocarbon and of the allyl system present in the EPDM terpolymer. AIBN (0.13%) was used as initiator. 

At time t = 0 the sample is put into contact with the supply of liquid hydrocarbon (n-hexane or benzene) in equilibrium with the gas and is then placed quickly in the magnet. The liquid phase is either pure or consists of a mixture such that the two partial presstnes of the gases are equal to 60 mbar (assuming that the mixture obeys Raoult s law). To distinguish the hydrocarbons when they are mixed, one is perhydro and the other perdeutero. 

Figure 33. Various equivalent representations for the hydrocarbon n-hexane (QHm).

The sorption and transport of four aliphatic hydrocarbons (n-hexane, n-heptane, n-octane and n-nonane) into NR crosslinked using conventional, efficient, dicumyl peroxide(DCP) and mixed sulphur/peroxide vulcanisation systems were investigated at temp, of 28 to 60C. The NR vulcanised by DCP exhibited the lowest penetrant uptake of the systems studied. It was observed that the kinetics of liquid sorption in every case deviated from the regular Fickian trend, characteristic of sorption of liquids by rubbers. The diffusion coefficient, activation energy of sorption, enthalpy, entropy and rubber-solvent interaction parameter were evaluated for the four systems from the swelling data. 30 refs. 

Fig. Ill-16. Surface tension lowering of water at 15°C due to adsorption of hydrocarbons. , n-pentane A, 2,2,4-trimethylpentane O, n-hexane x, n-heptane A, n-octane. (From Ref. 133.)...

Petroleum ether fractions free from aromatic hydrocarbons are marketed, as are also n-hexane and n-heptane from petroleum. 

Alhedai et al also examined the exclusion properties of a reversed phase material The stationary phase chosen was a Cg hydrocarbon bonded to the silica, and the mobile phase chosen was 2-octane. As the solutes, solvent and stationary phase were all dispersive (hydrophobic in character) and both the stationary phase and the mobile phase contained Cg interacting moieties, the solute would experience the same interactions in both phases. Thus, any differential retention would be solely due to exclusion and not due to molecular interactions. This could be confirmed by carrying out the experiments at two different temperatures. If any interactive mechanism was present that caused retention, then different retention volumes would be obtained for the same solute at different temperatures. Solutes ranging from n-hexane to n hexatriacontane were chromatographed at 30°C and 50°C respectively. The results obtained are shown in Figure 8. 

Paraffinic Hydrocarbons Methane Ethane Propane n-Butane 1-Butane n-Pentane n-Hexane... 

Triton X-100 polycyclic aromatic hydrocarbons 10-fold 1% solution in n-hexane optimal emission after 60 min 10% zone enlargement [234]... 

Heat of vaporization, 66 see also Vaporization Helium, 91 boiling point, 63 heat of vaporization, 105 interaction between atoms, 277 ionization energy, 268 molar volume, 60 on Sun, 447 source, 91 Hematite, 404 Hemin, structure of, 397 Hess s Law, 111 Heterogeneous, 70 systems and reaction rate, 126 n-Hexane properties, 341 Hibernation, 2 Hildebrand, Joel H.. 163 Holmium, properties, 412 Homogeneous, 70 systems and reaction rate, 126 Hydration, 313 Hydrazine, 46, 47, 231 Hydrides of third-row elements, 102 boiling point of. 315 Hydrocarbons, 340 unsaturated, 342... 

Gasoline contains more than 250 components of a mixture of C4-C12 hydrocarbons, which varies in concentration from batch to batch. Some of these components are isobutane, n-butane. isopentane, n-pentane, 2,3-dimethylbutane, 3-methylpentane, n-hexane, 2,4-dimethylpentane, benzene, 2-methylhexane, 3-meth-ylhexane, 2,2,4-trimethylpentane, 2,3,4-trimethylpentane, 2,5-dimethylhexane, 2,4-dimethylhexane, toluene, 2,3-dimethylhexane. ethylbenzene, methylethylbenzenes, m-, p-, and o-xylene, trimeth- ylbenzenes, naphthalene, methylnaphthalenes, and dimethylnaph-thalenes... 

Hologenated hydrocarbons 100/a n-Hexane 100/a Hydrazine 0.25/a Hydrocarbon 0.1 %/b Hydrocarbon 2 Hydrocarbon test Hydrochloric acid 1/a... 

As naphtha contains many hydrocarbons in the range of C5-C10, the reformate product is a complex mixture of a few hundred different molecules. n-Hexane is the... 

An important application of the critical solution temperature is to the determination of the water content in such substances as methyl and ethyl alcohols. Here the system is usually the alcohol and a hydrocarbon, such as n-hexane or dict/c/ohexyl the water is, of course, insoluble in the hydrocarbon. Thus, the methyl alcohol - cyclohexane system has a C.S.T. of 45-5° and even 0-01 per cent, of water produces a rise of 0-15° in the C.S.T. The experimental details are given below. 

The substance is examined in a dilute solution in a solvent. A wide choice of solvents, transparent to ultraviolet radiation, is available. The paraffin hydrocarbons are all suitable, as are the ahphatic alcohols and the chlorinated hydrocarbons, such as chloroform and carbon tetrachloride. The most useful solvents are n-hexane, cyclohexane, chloro-... 

The most critical decision to be made is the choice of the best solvent to facilitate extraction of the drug residue while minimizing interference. A review of available solubility, logP, and pK /pKb data for the marker residue can become an important first step in the selection of the best extraction solvents to try. A selected list of solvents from the literature methods include individual solvents (n-hexane, " dichloromethane, ethyl acetate, acetone, acetonitrile, methanol, and water ) mixtures of solvents (dichloromethane-methanol-acetic acid, isooctane-ethyl acetate, methanol-water, and acetonitrile-water ), and aqueous buffer solutions (phosphate and sodium sulfate ). Hexane is a very nonpolar solvent and could be chosen as an extraction solvent if the analyte is also very nonpolar. For example, Serrano et al used n-hexane to extract the very nonpolar polychlorinated biphenyls (PCBs) from fat, liver, and kidney of whale. One advantage of using n-hexane as an extraction solvent for fat tissue is that the fat itself will be completely dissolved, but this will necessitate an additional cleanup step to remove the substantial fat matrix. The choice of chlorinated hydrocarbons such as methylene chloride, chloroform, and carbon tetrachloride should be avoided owing to safety and environmental concerns with these solvents. Diethyl ether and ethyl acetate are other relatively nonpolar solvents that are appropriate for extraction of nonpolar analytes. Diethyl ether or ethyl acetate may also be combined with hexane (or other hydrocarbon solvent) to create an extraction solvent that has a polarity intermediate between the two solvents. For example, Gerhardt et a/. used a combination of isooctane and ethyl acetate for the extraction of several ionophores from various animal tissues. 

In the present chapter, we report about an inveshgahon of the catalyhc performance of rahle-type V/Sb and Sn/V/Sb/Nb mixed oxides in the gas-phase ammoxidation of n-hexane. These catalysts were chosen because they exhibit intrinsic mulhfunctional properties in fact, they possess sites able to perform both the oxidahve dehydrogenahon of the alkane to yield unsaturated hydrocarbons, and the allylic ammoxidahon of the intermediate olefins to the unsaturated lutriles. These steps are those leading to the formahon of acrylonitrile in propane ammoxidahon. The SnW/Sb/(Nb)/0 system is one of those giving the best performance in propane ammoxidahon under hydrocarbon-rich condihons (8,9). 

Due to the narrow safe area in the hydrocarbon-lean zone, operation in the n-hexane-rich zone was preferred. In the latter case, however, feed compositions having high hydrocarbon concentration had to be avoided, in order to hmit the contribution of radical-chain reactions, favoured at high temperature under aerobic conditions. Therefore, operation with a diluted feed was preferred the ballast used for the reaction was helium, in order to allow evaluation of the amount of N2 produced by ammonia combustion. 

Hydrocarbon-rich conditions imply that oxygen is the limiting reactant, due to the high oxygen-to-hydrocarbon stoichiometric ratio in n-hexane ammoxidation. Therefore, the conversion of the hydrocarbon is low this should favour, in principle, the selectivity to products of partial (amm)oxidation instead of that to combustion products. 

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